Question 1.
An isotope has a half-life of 6 hours. If the original sample had a mass of 500 grams, how much of the sample would be left after 30 hours. Be sure to identify the number of 1/2 life that occurred and to explain how you obtained this answer.

Question 2.
Calculate the percent by mass of water in Copper (II) Fluoride tetra hydrate. You must show all of your work to earn credit. Atomic masses of each element: Cu = 64, F = 19, O = 16, H= 1

Question 3.

If the percent (mass/mass) for a solute is 16% and the mass of the solution is 400 g, what is the mass of solute in solution?

A.6400 grams
B. 25 grams
C.64 grams
D. 0.04 grams

Answer:

a spectrum of the electromagnetic radiation emitted by a source.

D

Explanation:

A. The photons emitted when an electron drops down an energy level.

When a source emits electromagnetic radiation then the spectrum is called as emission spectrum. It is emitted during the process when an atom makes its transition of energy levels to ground state.

Ground state is the state where atom possesses the lowest energy. When an atom or molecule comes down from higher energy level to lower energy level, it emits the spectrum which is called as emission spectrum.

Answer: The correct answer is "It's the tendency for the body to resist a change in motion".

Explanation:

Newton's First Law of motion addresses a body at rest or in motion. This law is also known as "Law of inertia".

Inertia resists any change in the state of the object. Mass is a measure of inertia.

If the object is in motion then it remains in this state or if the object is at rest then it remains in this state unless the external force is applied.

If the object is moving with constant velocity then it will remain moving with this velocity unless it is accelerated.

Suppose, bus driver applies suddenly applies brake. The passenger sitting inside the bus falls forward. It is due to inertia. As the passenger does not want to change its state. It resists this change. The upper part of the body wants to remain in the state of motion. It's the tendency for the body to resist a change in motion

Therefore, the correct option is (D).

your answer should be C.

MARK ME BRAINLIEST PLEASE!

Answer: The correct answer is Option c.

Explanation:

All the radioactive reactions follows first order kinetics.

The equation used to calculate half life for first order kinetics:

[tex]t_{1/2}=\frac{0.693}{k}[/tex]

We are given:

[tex]t_{1/2}=1hr[/tex]

Putting values in above equation, we get:

[tex]k=\frac{0.693}{1}=0.693hr^{-1}[/tex]

Rate law expression for first order kinetics is given by the equation:

[tex]k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}[/tex]

where,  

k = rate constant = [tex]0.693hr^{-1}[/tex]

t = time taken for decay process = 3.00 pm - 12.00 pm = 3 hour

[tex][A_o][/tex] = initial amount of the reactant = 20 g

[A] = amount left after decay process =  ?

Putting values in above equation, we get:

[tex]0.693hr^{-1}=\frac{2.303}{3hr}\log\frac{20}{[A]}[/tex]

[tex][A]=2.5g[/tex]

Hence, the correct answer is Option c.

Your answer would be False

Answer: It would be false. thank me later.

Try this solution, all the details are described in the attached picture.

Answer:

D. 15,000.

Explanation:

KE = (3/2)KT

Where, KE is the kinetic energy of the molecules (J),

K is the Boltzmann constant (1.381 × 10⁻²³ J/K),

T is the temperature (K) 

So, the right choice is: D. 15,000

Answer: D. 15,000.

Explanation: Founders Educere answer. And whatever that dude said^

If a neutral atom becomes negatively charged, it has undergone reduction.

Reduction is the process through which a neutral atom gain an electron (thus reducing its oxidation number) and turns into a negative ion (also known as : anion)

So basically none of the above

If a neutral atom becomes negatively charged, it has undergone reduction. Hence, option C is correct.

An atom contains a central nucleus surrounded by one or more electrons.

Protons are bound in the nucleus and can be neither gained nor lost. So any change in the charge of an atom is due to changes in its electron count. If a neutral atom gains electrons, then it will become negatively charged. If a neutral atom loses electrons, then it becomes positively charged.

The loss of electrons is the corresponding increase in the oxidation state of a given reactant is called oxidation. The gain of electrons and the decrease in the oxidation state of a reactant is called reduction.

Reduction is the process through which a neutral atom gains an electron (thus reducing its oxidation number) and turns into a negative ion (also known as an anion).

Hence, option C is correct.

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Answer:

1.overcome the attractive forces of other liquid particles

3.gain energy

Explanation:

A phase change from liquid to solid occurs when heat energy is added to the system. The heat energy gives the liquid molecules more kinetic energy and the attractive forces between the particles are overcome. When the molecules of liquid gains sufficient energy, they are free to move in all directions that they want, thus becoming gases.

Explanation:

In liquids, the molecules are held by less strong intermolecular forces of attraction as compared to solids. Due to which they are able to slide past each other. Hence, they have medium kinetic energy.

On the other hand, in gases, the molecules are held by weak Vander waal forces. Hence, they have high kinetic energy due to which they move rapidly from one place to another leading to more number of collisions.  

Hence, gases are able to expand more rapidly as compared to liquids.

Therefore, we can conclude that in order for a liquid particle to become a gas it must:

Answer:

A. The Cl- ions become oxidized at the cathode allowing them to form Cl2 molecules.

Explanation:

At the anode in an electrolytic cell oxidation occurs.

In the electrolysis of NaCl, at the anode both Cl⁻ and OH⁻ migrates here.

Cl⁻ is preferentially discharged and it undergoes oxidation as shown below:

2Cl⁻ → Cl₂ + 2e⁻

We see a loss of electron and change in oxidation number of Cl from -1 to 0

Chlorine gas is liberated in this electrode.

Answer:

The Cl- ions become oxidized at the cathode allowing them to form Cl2 molecules.

Explanation:

Answer via Educere/ Founder's Education

Answer:

D.These elements tend to gain or lose electrons easily is incorrect.

Explanation:

Noble gasses consist of atoms that have full rings of electrons. Electrons are what bond atoms together to create chemical compounds, and incomplete rings are needed for the process.

D. These elements tend to gain or lose electrons easily

The gases which are considered as Nobel are generally nonreactive. Truth be told, they are the least responsive components on the periodic table. This is on the grounds that they have a total valence shell. They tend to pick up or lose electrons rarely.

In 1898, Hugo Erdmann begat the expression “Nobel gas” to mirror the low reactivity of these components, similarly as the respectable metals are less receptive than different metals. These gases have high energies of ionization and immaterial electronegativities. These gases have low breaking points and are on the whole gases at room temperature.

Answer:

c hopes this helps u pass or whatever

An ionic compound has a chemical formula that shows the ions in a molecule.

Ionic compounds are held by the electrostatic attraction between the atoms. The ionic compounds are formed by ions of different charges.

(a) The chemical formula of ionic compounds has a number subscript which indicates the number of atoms of the ion.

(b) The formula unit does not give the number of ions.

(c) The ionic compounds are not necessarily neutral as the charge difference between anion and cation results in the charged compound.

(d) The chemical formula of an ionic compound represents the ions in a molecule.

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The enthalpy of this reaction is 0.882 kJ/mol.

Given the following data:

We know that the specific heat capacity of water is 4.184 J/g°C.

To find the enthalpy of this reaction:

First of all, we would determine the quantity of heat energy that was used during this chemical reaction by using the formula;

[tex]Q = mc\theta[/tex]

Where:

[tex]\theta = T_2 - T_1\\\\\theta = 24.70 - 21.00\\\\\theta = 3.70[/tex]

Substituting the values into the formula, we have:

[tex]Q = 114[/tex] × [tex]4.184[/tex] × [tex]3.70[/tex]

Quantity of heat, Q = 1764.81 Joules

Now, we can find the enthalpy of this reaction by using the formula;

[tex]Enthalpy = \frac{Energy}{Number\; of\; moles}[/tex]

Substituting the parameters into the formula, we have:

[tex]Enthalpy = \frac{1764.81}{2.00}[/tex]

Enthalpy = 882.405 J/mol.

In Kilojoules per mole of compound to three significant figures:

Note: 1 Kilojoules = 1000 Joules

[tex]Enthalpy = \frac{882.405}{1000}[/tex]

Enthalpy = 0.882 kJ/mol.

Therefore, the enthalpy of this reaction is 0.882 kJ/mol.

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To find the enthalpy of the reaction, we first calculate heat change with the equation q = msΔT, where m is mass, s is the specific heat, and ΔT is the change in temperature. The calculated heat energy is then divided by the number of moles of the compound to find the enthalpy. Thus, the enthalpy for the reaction described is approximately 0.886 kJ/mol.

To calculate the enthalpy of the reaction, we first need to calculate the heat change, noted as q. The equation for q in a reaction is q = msΔT where m is mass, s is the specific heat, and ΔT is the change in temperature.

First, transform the 114 grams of solution into mL since the density of water is approximately 1.0 g/mL. So the mass of the solution is 114 mL.

The change in temperature (ΔT) is 24.70°C - 21.00°C = 3.70°C. The specific heat (s) of water is 4.18 J/g°C. Using these figures, the calculation becomes: q = (114 g)(4.18 J/g°C)(3.70°C) = 1772.428 J or 1.772 kJ (keep in mind 1 kJ = 1000 J).

To find the enthalpy, which is expressed as kJ/mol, we divide the heat energy change by moles. So, the enthalpy = q (in kJ) / moles = 1.772 kJ / 2.00 mol = 0.886 kJ/mol.

Therefore, the enthalpy of this reaction is approximately 0.886 kJ/mol.

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Boiling point is the only answer that doesn’t have to do with their physical property

Answer:

D) ability to combine with oxygen

Explanation:

D because oxygen is not visible so that is not a physical property

Answer:

3 x = 3.

Value of x = 1 and y = 10.

Explanation:

-2x + y = 8

5x - y = -5

5x + (-2x) + y + (-y) = 8 + (-5)

∴ 3 x = 3.

∴ x = 1.

-2(1) + y = 8.

∴ y = 10.

Answer:

3x =  3

Explanation:

Got it right on edge 2020 :)

Boils at -40 C (or F, same same) so colder than that it would be a clear stable liquid.

Answer:

At or below -42°C

Explanation:

Hello,

As propane is gaseous at the standard sea level wherein the atmospheric pressure is 1 atm and the environmental temperature roughly 25°C, in order to condense it, say convert it from gas to liquid, one must cool it down at least until its boiling temperature which is -42°C. In such manner, to remain as a liquid, it must be cooled down at or below 42°C.

Best regards.

Answer: The correct answer is Option D.

Explanation:

A non-polar covalent bond is defined as the bond which is formed between the atoms having no difference in electronegativity values. For Example: [tex]Cl_2,H_2[/tex] etc..

In this bond, the electrons are shared equally and [tex]\Delta EN[/tex] value is equal to 0.

Hence, the correct answer is Option D.

The correct answer is D. A nonpolar covalent bond is a type of covalent bond where electrons are shared equally between two atoms due to equal electronegativities.

The equal sharing occurs because the atoms have identical or nearly identical electronegativity values, meaning neither atom attracts the shared electrons more than the other. An example of a nonpolar covalent bond can be found in a molecule of chlorine, where both chlorine atoms share the electrons equally.

Answer:

Explanation:

Electrolysis of aqeous sodium chloride(NaCl)

Electrolysis is a process that converts electrical energy into chemical energy.

Electrolytic processes involves three major steps:

1. Ionization of electrolyte and water

2. Migration of ions to electrodes

3. Discharge of ions at the electrodes.

For the Electrolysis of brine, we follow these three steps:

1. Ionization of the aqeous brine solution:

NaCl → Na⁺ + Cl⁻

H₂O ⇄H⁺ + OH⁻

2. Migration of ions to the electrodes

The positive charges Na⁺ and H⁺ would both go to the cathode which is the negatively charged electrode

The negative charges Cl⁻ and OH⁻ migrates to the anode which are the positively charged electrodes. The anode is positively charged electrode.

3. Discharge of ions at the electrodes.

The preferential discharge of ions is based on the activity series and concentration of the ions.

On the activity series H is lower and it discharges preferentially to Na in the cathode:

2H⁺ + 2e⁻ → H₂

At this electrode, the cathode, reduction occurs and H⁺ ions are reduced.

At the anode Cl⁻ and OH⁻ migrates. But Cl⁻ is discharged preferentially due to its higher concentration.

2Cl⁻ ⇄ Cl₂ + 2e⁻

This is the oxidation half and Cl is oxidized

To calculate the delta H for the dissolution of KCl in water, use the heat equation q = mcΔT with the given mass, specific heat capacity of water, and the temperature change. Then, convert q to kilojoules and divide by the number of moles of KCl to find the enthalpy change per mole.

The question pertains to thermochemistry, a branch of chemistry that deals with the heat involved in chemical reactions and physical transformations. We need to calculate the enthalpy change (delta H) when KCl dissolves in water, which involves using the formula q = mcΔT, where q is the heat absorbed or released, m is the mass of the solvent (water), c is the specific heat capacity, and ΔT is the change in temperature.

First, we identify the temperature drop: ΔT = 21.6°C - 31.0°C = -9.4°C. This indicates that the solution absorbed heat (since the temperature of the water dropped, the reaction is endothermic). Then, using the specific heat capacity of water (4.18 J/g°C), we calculate q as follows:

q = mcΔT
= (75.0 g)(4.18 J/g°C)(-9.4°C)
= -2969.4 J

Since specific heat capacity and mass are both positive, the negative q value signifies that the heat was absorbed by the substance from the water. To find delta H in kJ/mol, we convert the mass of KCl to moles using its molar mass (74.55 g/mol) and then divide q by the number of moles:

Moles of KCl = 12.8 g / 74.55 g/mol
Approximately = 0.172 moles

Delta H = q / moles
= -2969.4 J / 0.172 mol
= -17261 J/mol

Since we need delta H in kilojoules per mole, we convert J to kJ:

Delta H = -17261 J/mol / 1000 J/kJ
= -17.261 kJ/mol

As the delta H is negative, it confirms that the dissolution of KCl in water is an endothermic process.

Answer:

Explanation:

The parameter to predict the spontaneity of a reduction is the change in the free energy, ΔG.

This is how it works:

In brief, free energy's decrease tells that a reaction is spontaneous, while free energy's increase tells a reaction is nonspontaneous.

Now, take the definition of the free energy:

The conditions given in the statement are:

Replacing in the equation ΔG = ΔH - TΔS, you get:

Then, you conclude that for an endothermic reaction with a negative entropy change, the change in the free energy is positive, and so the reaction is nonspontaneous (at all temperatures) in the forward direction.

Since, the change in the reverse direction has opposite sign, you also conclude that the reaction is spontaneous in the reverse direction at all temperatures.

Answer:Sample Absorbance (625 nm)  

A 0.536  

B 0.783  

C 0.045  

Therefore, I will use these data to solve your question. If you have other absorbances values, just follow my steps and plug in different numbers.

First, we see 1 mole of NH3 gives 1 mole product.

In B moles of NH3 = moles of NH3 in A + (5.5 x10^-4 x2.5/1000) = 1.375 x10^6 + mA

( mA = moles of NH3 in A) vol of B = 25 = vol of A

now A = el C = eC ( since l = 1cm)

Because, n net absorbance due to complex blank absorbance must be removed.

Here A(A) = 0.536 - 0.045 = 0.491 , A(B) = 0.783 - 0.045 = 0.738  

(you can plug in different numbers in this step)

A2/A1 = C2/C1 , A(B)/A(A) = (1.375x10^-6 +mA)/(mA) = 0.738/0.491

So, mA = 2.733 x 10^-6 = moles of NH3 in A (Lake water)

Hence [NH3] water ( 2.733 x10^-6 ) x 1000/25 = 1.093 x 10^-4 M

Lake water vol = 10 ml out of 25,

Concentration of ammonia in lake water = 2.733 x10^-6 x 1000/10 = 2.733 x 10^-4 M

Then, A = 0.491 = e x 1 x 1.093 x10^-4

e = 4492 M-1cm-1

Explanation:

The molar absorptivity (ε) of the indophenol product, as calculated using the Beer-Lambert law and the known concentration and measured absorbance of Sample B, is 12109.09 M^-1 cm^-1. To find the concentration of ammonia in the lake water, we subtract the absorbance of the reagent blank from the absorbance of Sample A, then use the Beer-Lambert law to solve for the concentration. It results in 0.000031 M, or 3.1x10^-5 M.

To find the molar absorptivity (ε), we can use the Beer-Lambert law, which states that the absorbance (A) of a solution is directly proportional to its concentration (c) and the path length (l) through which the light passes. The formula is A = εlc. In this case, the path length is a constant 1.00 cm, so we can rearrange the formula to solve for ε: ε = A / (l * c).

Sample B contains a known amount of NH3. From this, we know that the concentration of NH3 in the solution is (2.50 mL * 5.50x10^-4 M) / 25 mL = 0.000055 M. Using the measured absorbance for sample B (0.666), we can solve for ε: ε = 0.666 / (1.00 cm * 0.000055 M) = 12109.09 M^-1 cm^-1.

To find the concentration of ammonia in the lake water, we subtract the absorbance of the reagent blank (C) from the absorbance of sample A, which contains an unknown amount of NH3. This gives us the absorbance due to the NH3 in the lake water: A' = 0.419 - 0.045 = 0.374. We can then use the Beer-Lambert law to solve for the concentration of NH3: [NH3] = A' / (ε * l) = 0.374 / (12109.09 M^-1 cm^-1 * 1.00 cm) = 0.000031 M, or 3.1x10^-5 M.

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Answer:

c) 8 protons 10 electrons

Because there would usually be 8 of both, but in this case there has to be 2 more electrons to give it the ²⁻ charge

a because as temperature increases, reaction rate increases.

Answer:

The correct answer is the table of point A.

Explanation:

An increase in temperature increases the speed of reaction, regardless of whether the reaction is endothermic or exothermic. This is because as the temperature increases, the number of molecules with an energy equal to or greater than the activation energy increases, thus increasing the number of effective shocks.

Have a nice day!

D. ( Neither ultrasonic nor infrasonic vibrations can be heard by humans. )

Answer:

The correct statement is option D, that is, neither ultrasonic nor infrasonic vibrations can be heard by humans.

Explanation:

The ultrasonic vibrations are the sound waves exhibiting the frequency of more than 20000 Hz, whereas the upper-frequency limit in human beings is about 20 Hz. Humans cannot hear the ultrasound as it is more than 20 Hz.  

On the other hand, the infrasonic vibrations refer to a low-frequency sound, it is lower in frequency in comparison to 20 Hz, that is, the usual limit of human hearing. Thus, for humans to perceive infrasound, the pressure of the sound must be adequately high.  

Answer:

2. Inorganic

Explanation:

All man-made and most carbon-based compounds are inorganic

Answer:

inorganic

Explanation:

Answer:

[tex]\boxed{\text{Ba}^{2+}}[/tex]

Explanation:

[tex]\rm 2H^{+} + CrO_{2}^{3-} + \textbf{Ba}^{2+} + 2OH^{-} \longrightarrow \textbf{Ba}^{2+} + CrO_{2}^{4-} + 2H_{2}O[/tex]

The spectator ions are the ions that are on both sides of the equation.

[tex]\text{In this equation, the spectator ions are }\boxed{\textbf{Ba}^{2+}}.[/tex]

They are present at the beginning and at the end of the reaction. They don't take part in the reaction. They are simply "spectators" watching the other ions "do their thing."

Spectator ions remain unchanged during a chemical reaction and are crucial in identifying the net ionic equation.

When looking at the total ionic equation 2H+ + CrO2 3- + Ba2+ + 2OH-
ightarrow Ba2+ + CrO2 4- + 2H2O, spectator ions are those that do not participate in the reaction and are present in the same form on both the reactant and product sides of the equation. In this case, the Barium ion (Ba2+) is the spectator ion since it does not change from reactants to products.

Spectator ions are ions that do not participate in a chemical reaction and remain unchanged during the reaction. They can be identified by observing which ions are present on both sides of the equation with the same coefficients. By canceling out the spectator ions, you can obtain the net ionic equation, which focuses only on the species directly involved in the reaction.

Answer:

C. Compound

Explanation:

NaCl is a combination of two elements. This is specifically an ionic compound.

Sodium chloride is a compound.

A chemical compound exists as a chemical substance comprised of many identical molecules composed of atoms from more than one component held together by chemical bonds. Compounds exist as chemical substances made up of two or more elements that exist chemically bound together in a fixed ratio. All the subject in the universe is composed of atoms of more than 100 various chemical elements, which exist found both in pure form and incorporated into chemical compounds. Chemical compounds exist formed by elements that bond together. These bonds stand generally covalent, ionic, or metallic bonds.

The correct solution is option C.

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Answer: Alkaline earth metals, as this is shown by its location on the periodic table

Mg is a member of the c) alkaline earth metals family.

Group 2A (or IIA) of the Periodic Table is an alkaline earth metal. Beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra). They are harder and less reactive than Group 1A alkali metals.

Alkaline earth metals are named after the alkaline earths called beryllium, magnesia, limestone, strontium, and barite after their oxides. When mixed with water, these oxides are simple (alkaline).

The main difference between alkali metals and alkaline earth metals is that all alkali metals have one electron in the outermost shell, whereas all alkaline earth metals have two external electrons. That is.

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Final answer:

Smaller marble chips react faster with acid due to the increased surface area, leading to a greater loss of mass in the same time frame compared to larger chips. Hence, the best description is that small chips would lose 4 grams over 7 minutes (option C).

Explanation:

When considering the reaction of marble chips with acid, the rate at which the reaction occurs depends largely on the surface area of the marble that is exposed to the acid. Smaller chips have a larger surface area relative to their volume, allowing more acid to come into contact with the chips, thus increasing the rate of the reaction. Marble (Ca[tex]CO_{3}[/tex]) reacts with hydrochloric acid (HCl) to form calcium chloride, water, and carbon dioxide gas. As the reaction proceeds, the mass of the marble decreases because carbon dioxide gas is released and escapes into the air.

Based on this explanation, option C is the best description of how small chips would react: The small chips would react faster, losing 4 grams over the same 7 minutes. This is because the small chips provide a greater surface area for the acid to react with, leading to a faster reaction rate and therefore a greater loss of mass in the same amount of time compared to larger chips.

The correct answer is A. Brainliest would be much appreciated.

The oxidation state of [tex]Fe_2O_3[/tex] is +3. The bond formation between oxygen and iron depends on the difference in electronegativity between these two atoms. It starts with a charge of +3 and is reduced. Hence, option A is correct.

The total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom.

Oxygen in nearly all cases has a charge of 2−, so the total ionic charge the O atoms exhibit is 3(−2)=−6 .

If two Fe atoms equalize this charge and make it neutral, the charge (oxidation state) of Fe in this compound must be 3+.

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are a type of force acting between atoms and molecules.[1] They are part of the van der Waals forces. The LDF is named after the German-American physicist Fritz London.

First of all, disperse means to break away.

So dispersion forces are forces that cause molecules to break away from each other. Dispersion forces are a very very weak force because the molecules are not attracted to each other because they disperse or move away.